Acceleration responsive switch



Aug. 26, 1958 P. v. N. HELLER ACCELERATION RESPONSIVE SWITCH 2 Sheets-Sheet l m. R u m WM. 0 NM I I m n P ATTORNEV Filed Aug. 6, 1953 CONTROL LOAD Aug 26, E958 P. v. N. HELLER ACCELERATION RESPONSIVE SWITCH 2 Sheets-Sheet 2 Filed Aug. 6, 1953 ACCELLERAT/ON INVENTOR. PETER l/. N. HELLER ATTORNEY 2,849,562 Patented Aug. 26, 1958 ACCELERATKUN RESPONSHVE SWITCH Peter V. N. Heller, Pasadena, Calif. Application August 6, 1953, Serial No. 372,767

13 Claims. (Cl. t)-9ll) This invention relates to electric switches which are responsive to accelerations and it is primarily concerned with switches for use in vibratory systems such as electric vibrators.

Electric switches which employ mercury as the switching element are ordinarily operated by controlling the attitude of a container in which the mercury is located. The position of the mercury in the container is governed by the laws of gravity; hence the mercury seeks the lowest portion of the'container.

I have discovered that a switch employing a liquid switching element such as mercury operates substantially independently of the attitude of the switch and is responsive to accelerations if the liquid is located in a chamber of varying cross-sectional area and if the molecular cohesion of the liquid causes it to be positioned in the portion of the chamber of largest cross-sectional area when the chamber is at rest and to move into portions of the chamber having smaller cross-sectional area only when the container is accelerated or decelerated along certain directions.

The molecular cohesion of mercury causes a globnle of it to assume a spherical shape when the mercury is unconfined. If the globule of mercury is confined in a chamber having a centrally located portion of greater cross-sectional area than that of the remaining portions of the chamber, and if the globule of mercury has a volume which causes it to extend throughout the portion of the chamber of greatest cross-section but not throughout all of the remaining portions of the chamher when the chamber is at rest, then the mercury will move into portions of the chamber of smaller crosssectional area only when the chamber is accelerated or decelerated.

I prefer to provide a chamber having a cross-section of approximately elliptical shape in a plane extending along the direction of movement of the container. The major axis of the ellipse may extend parallel to or it may be inclined with respect to the direction of movement of the container.

if a globule of mercury which assumes spherical shape having a diameter of the order of .036 inch in free space is confined in a chamber having an elliptical cross-section of such dimensions that the globule of mercury is slightly squashed at all times, an acceleration or a deceleration of to 50 times the force of gravity is required to cause the mercury to move into the most confining portions of the chamber, i. e. into the extremities of the chamber.

-ccelerati0n-responsive switches of this type are ticularly useful in electric vibrators and the like. The switches can be used in substantially any position, and they have a long life without requiring any maintenance.

The invention is explained with reference to the drawings, in which:

Fig. 1 shows an embodiment of the switch of my invention employed in an electric vibrator, the switch being shown in section;

par-

Fig. 2 is a sectional view of an embodiment of the switch which may be employed as a chopper in a vibratoIfy system;

Fig. 3 illustrates the position which the liquid switching element assumes when the switch of Fig. 2 is accelerated in the direction of the arrow;

Fig. 4 is an end view of the switch of Fig. 2 taken from the right-hand end of Fig. 2;

Fig. 5 is a sectional View showing a modification of the embodiments of Figs. 1 to 4, wherein a double reed is employed to support the switch;

Fig. 6 shows how the electrical connections for the embodiment of Fig. 2 may be completely shielded;

Fig. 7 is a sectional view showing an embodiment of the switch in which the mercury switching element moves around the periphery of the chamber;

Fig. 8 is a sectional view along line 8-8 of Fig. 7;

Fig. 9 shows a modification of the switch of Fig. 7 arranged to provide a closed circuit periodically between the two halves of the enclosure member;

Fig. 10 is a sectional view along line iii-16 of Fig. 9; Fig. 11 shows how the mercury switching element of the embodiments shown in Figs. 7 to 10 moves around the periphery of the chamber when the member is accelerated back and forth;

Fig. 12 shows a preferred arrangement for actuating a double reed vibratory member;

Fig. 13 is a sectional view along line 13-13 of Fig. 12 showing a shielding arrangement for the vibrator;

Fig. 14 shows another shielding arrangement for a vibrator; and

Fig. 15 shows a double reed support for a vibratory member wherein the reeds are employed as conductors for providing electrical circuits to the contacts which engage the mercury switching element.

With reference to Fig. 1, a conductive liquid in) having high molecular cohesion, such as mercury, is employed as the switching element in an electric vibrator. The mercury is located in a chamber in a container 21 which comprises a conductive cylindrical member- 22 and a pair of non-conductive end pieces 524 26. In this embodiment of the invention, the chamber has a cross-section of approximately elliptical shape in any plane which extends along the direction of vibration of the member. Thus, the chamber is shaped like a football, and its major axis extends parallel to the direction of vibration of the member.

The'mercury has a volume which causes it to extend the length of the minor axes of the elliptical-shaped chamber, but less than the length of the major axis of the chamber. Hence, the globule of mercury is slightly squashed at all times, and the molecular cohesion of the mercury causes it to be located in the portions of the chamber of greatest cross-section when the memher is at rest. This is because the mercury tends to assume the most nearly spherical shape possible, and hence the molecular cohesion of the mercury causes the mercury to seek the least confining portions of the chamber. I

When the chamber is accelerated or decelerated along the direction of its major axis, the inertia of the mercury causes. it to move into the end portions of the chamber which are of smaller cross-section.

A pair of electrical contacts 23, 3b are located at the ends of the chamber for engaging the mercury when it is in predetermined positions in the chamber. In the embodiment of Fig. l, the contact 28 extends further into the chamber than the contact 30, so that the contact 2? engages the mercury when it is at rest, but contact engages the mercury only when the Qt mercury is caused to move into the more confining portion of the chamber adjacent the contact 30.

The central portion of the interior of the cylindrical member 22 contacts the mercury at all times. Thus, an electric circuit is alternately provided through the mercury to the cylindrical member 22 by the contacts 23 and 3%) when the mercury moves back and forth along the major axis of the chamber.

The cylindrical member 22 is supported by a resilient reed 32, which may be integral with the member 22 or a separate part. The reed 32 is part of the electric circuit for the switch; hence it should be composed of a conductive material.

The cylindrical member 22 is composed of magnetic material, and an electromagnet 34 serves to accelerate the member 22 toward the pole piece of the electromagnet each time that it is energized.

A pulsating current for energizing the electromagnet is provided by a source of potential 36 through the electrical circuit which comprises the reed 32, the cylindrical member 22, the mercury 20, the contact 28, and an adjustable resistor 38. The resistor 38 controls the magnitude of the pulsating current and provides some control over the amplitude of vibration of the container 21.

The electrical circuit from the source of potential 36 through the mercury and the contact 3t? may be employed to provide a pulsating electric current to a load 40.

It is to be noted that the contact 28 provides an electric circuit through the mercury 24 when the mercury is at rest so that the vibrator of Fig. 1 is self starting. When the container 21 is accelerated to the left, the mercury 2t! moves toward the right hand end of the chamber. When the container 21 is decelerated the mercury 20 moves toward the left end of the chamber so that it disengages the contact 28 and engages the contact 3%. This de-cnergizes the electromagnet 34 and the reed 32 causes the container 21 to be accelerated toward the right. This causes the mercury to remain in the left end of the chamber until the container 21 is decelerated due to the action of. the reed. whereupon the mercury moves into the right hand end of the chamber to engage the contact 28 and cause the cycle of operation to be repeated.

Fig. 2 shows a modification of the switch of Fig. 1.

wherein the pair of electrical contacts 28, located at the ends of the chamber extend the same distance into the chamber and wherein both the contacts 28 and 30 are positioned so that they do not engage the globule of mercury 52! when it is centrally located in the chamber.

The embodiment of the switch shown in Fig. 2 is primarily suitable for use as a chopper wherein an electric circuit is alternately produced between the member 22 and the contacts 28, 30' when the globule of mercury moves back and forth in the chamber.

The switch of Fig. 2 may be caused to vibrate back and forth'in various ways. Ordinarily this is elfected by an electromagnet, such as shown in Fig. 1, which is energized with an alternating or a pulsating current.

Fig. 3 illustrates the action of the globule of mercury when the switch of Fig. 2 is accelerated to the right. When the switch is accelerated to the left the globule of mercury occupies a similar position in the right hand end of the chamber. Thus, as the container for the mercury vibrates back and forth, the mercury engages the contacts 28 and 30 alternately.

Fig. 4 is an end view of the switch of Fig. 2 illustrating a single reed arrangement for supporting the switch. If desired, a double reed 32' may be employed as illustrated in Fig. 5.

In many applications of the switch of Fig. 2 it is desirable to shield the electric circuits which are connected to the switch. Fig. 6 shows how shielding 42 and 44 may be employed with the switch of Fig. 2 so as to provide a complete electric shield for the circuits.

. For some uses, it is preferable to arrange the switch so that the major axis of the chamber in which the globule of mercury is located is inclined with respect to the direction of movement of the container. Figs. 7 to 10 show switches of this type, and Fig. 11 illustrates the movement of the globule of mercury when the switch is subjected to the accelerations indicated by the arrows. The accelerations indicated in Fig. ll represent typical vibratory motion for the switch. The vibrations of the switch cause the globule of mercury to move around the periphery of the elliptical chamber in synchronism with the vibrations. This motion of the mercury may be employed to effect various types of switching actions, as illustrated in Figs. 7 to 10.

In the embodiment of Figs. 7 and 8, the container for the mercury switching element comprises a pair of conivc side members 50, 52 with anon-conductive member located between the side members. A plurality of electric contacts 56 are located in the non-conductive member 54 for engaging the mercury as it moves around the periphery of the chamber. The mercury switching element may be employed to provide a short circuit between adjacent contacts 56 or between the respective contacts 56 and the side members 5%, 52. in the embodiment of Fig. 7, the contacts are closed continually when the switch is subjected to vibratory motion. That is, a short circuit is provided between a pair of the contacts at all times when the switch is subjected to vibratory motion which causes the mercury to be subjected to orbital movement around the periphery of the chamber.

The non-conductive member 54 and the two side members 5'6, 52". are hollowed out so as to provide a chamber of elliptical cross-section in a plane which extends along the direction of vibration of the member, with the major axis of the ellipse being disposed at approximately a 35 angle with respect to the direction of vibration.

If desired, a pair of inserts 58, 6d of non-conductive material may be employed on the faces of the side memhers in order to localize the contact area of the mercury on the side members and to provide insulation between he mercury and the side members 50, 5?. when the mercury is centrally located in the chamber.

The embodiment of Figs. 9 and 10 ditfers from that of Figs. 7 and 8 in that the mercury switching element serves to periodically provide a short circuit between the two side members 50, 52, and no contacts are employed in the central non-conductive member. A pair of insulators 62, 64, having corresponding shapes are located on the interior surfaces of the side members 50, 52, so that the mercury 20 provides a short circuit between the two side members 50, 52 only when it is located in portions of the chamber which are not bounded by the insulators 62 and 64.

The insulators may be of various shapes. The shape illustrated in Fig. 10 has a central portion 66 which is of circular outline, except for an indentation 68. The cen' tral portion 66 is shaped like the outline of the mercury when it is at rest, and the indentation 68 permits the mercury to contact the side member. Thus, this arrangement provides a short circuit between the two sides St), 52 when the mercury is at rest, and it provides periodic contact between the two sides 50, 52 when the member is subjected to vibration.

The embodiments of Figs. 7 to 10 employ a double reed for supporting the switch. The two reed members may be employed as part of the conductive circuit for the switch if desired.

Fig. 12 shows an arrangement for vibrating an acceleration-responsive switch which is supported by a double reed, and Fig. 13 shows how this arrangement may be shielded so that the magnetic fields do not induce electric signals in the switching circuit.

The acceleration responsive switch unit 70 is supported by a double reed 72 between the pole pieces of an electromagnet 74-, with the double reed members 72 arranged to straddle the lower pole piece of the electromagnet when the switch unit moves between the pole pieces.

a) i As shown in Fig. 13, a shield 76 may be'employed to prevent magnetic fields from inducing electric signals in the switching circuit. Fig. 14 shows another arrangement for actuating an acceleration-responsive switch, wherein the magnetic fields are shielded from the switching circuit. The acceleradon-responsive switch 80 may be the type shown in Fig. 6. The switch 80 is mounted on a non-magnetic reed 82 which extends on each side of the switch, and a member 84 composed of magnetic material is located at the free end of the reed. An electromagnet 86 serves to cause the magnetic head 84 to vibrate back and forth, and the vibrations are transmitted through the reed 82 to the switch 80. A magnetic shield 88 serves to prevent appreciable magnetic fields from reaching the switching circuit.

The arrangement of Fig. 14 is primarily suitable when the acceleration-responsive switch is employed as a chopper.

Fig. 15 shows how the members 94), 92 of a double reed support may be employed as the conductors for providing an electric circuit to contacts in the ends of an acceleration-responsive switch 94, suitable insulation being provided between the members 90, 92 and the body' of the switch 94.

In view of the foregoing, it will be apparent that wide variations may be made in the acceleration-responsive switching arrangements, as long as the liquid switching element is located in a chamber of varying cross-sectional area so that its location in the chamber is responsive to accelerations. Also, various arrangements other than the electromagnetic devices illustrated may be employed to subject the switches to accelerations and decelerations.

I claim:

1. An electric switch comprising a container defining a chamber elongated along an axis of revolution, the chamber having a varying cross-sectional area with maxi mum cross-sectional area at the central part of the chamber and tapering ofi in cross-sectional. area toward either end, a globule of conductive liquid located in the chamber and having a volume and a molecular cohesion which cause it to extend throughout the central portion of the chamber of largest cross-sectional area when the container is at rest and to move into portions at either end of the chamber of smaller cross-sectional area only when the container is accelerated in a direction parallel to said axis of revolution, and electrical contact means for engaging the conductive liquid when it is in predetermined positions in the chamber. 1

2. An electric switch comprising a container defining a hollow chamber elongated along an axis of revolution, the chamber having a varying cross-sectional area with maximum cross-sectional area at the central part of the chamber and tapering off in cross-sectional area toward either end, a globule of mercury located in the chamber and having a volume which causes it to extend throughout the central portion of the chamber of greatest crosssectional areawhen the container is at rest and to move into portions at either end of the chamber of smaller cross-sectional area when the container is accelerated in a direction parallel to said axis of revolution, and electrical contact means for engaging the mercury and providing an electric circuit through it only when the mercury is squeezed into either of the end portions of the chamber by acceleration forces applied to the container along said axis.

3. An electric switch comprising a member having a chamber therein elongated along an axis, the chamber having a centrally located portion of greater cross-sectional area than that of the remaining end portions of the chamber, a globule of mercury located in the chamber and having a cross-sectional area in natural unconfined condition that is slightly greater than the crosssectional area of the centrally located portion of the chamber, whereby the globule is caused to be centered at the portion of the chamber of largest cross-sectional area when the member is at rest and to move into the end portions of the chamber of smaller crosssectional area only when the member is accelerated in a direction parallel to the axis of elongation, and electrical contact means for engaging the mercury when it is in predetermined positions in the chamber.

4. An electric switch comprising a member having an elongated chamber therein, the chamber having a central portion of maximum circular cross-section and tapering off toward either end, a globule of conductive liquid located in the chamber, the liquid having a volume and a molecular cohesion which cause it to assume a substantially spherical shape in an unconfined condition of diameter greater than the diameter of the central portion of the chamber, whereby the globule in the absence of an accelerating force positions itself in the central portion of the chamber and moved into portions of the chamber of smaller cross-sectional area only when the member is accelerated in the direction of elongation of the chamber, and contact means inside the chamber for providing a predetermined electrical circuit with respect to the conductive liquid when the member is accelerated a predetermined amount so as to move the liquid into the portions of the chamber of smaller cross-sectional area.

5. An electrical switch comprising a vibratory container defining a chamber having a cross-section of approximately elliptical shape in a plane extending along the direction of vibration of the container, a globule of conductive liquid located in the chamber, the liquid having a molecular cohesion which causes it to assume a substantially spherical shape when in a free state and having a volume which causes it to extend the length of the minor axis of the ellipse but less than the length of the major axis of the ellipse, and contact means inside the chamber for engaging the liquid and providing an electrical circuit through the liquid when it is in a pre determined position in the chamber.

6. In a vibrating reed type relay having a vibratory member mounted on a resilient reed, and electromagnetic means for periodically accelerating the member along a predetermined direction, the improvement which comprises means in the vibratory member defining a chamber having an elliptical cross-section in planes extending along the direction of vibration of the member, with the major axis of the chamber being disposed approximately parallel with respect to the direction of vibration of the member, globule mercury located in the chamber and having a volume which causes the mercury to extend the length of the minor axis of the chamber but less than the length of the major axis of the chamber, and a pair of electrical contacts respectively located in the ends of the chamber for periodically engaging the mercury as it moves back and forth along the major axis of the chamber due to accelerations of the vibratory member.

7. In a vibrating reed type relay having a vibratory member mounted on a resilient reed, and an electromagnet for accelerating the member along a predetermined direction, the improvement which comprises means in the vibratory member defining a chamber having a cross-section of approximately elliptical shape in a plane extending along the direction of vibration of the member, with the major axis of the ellipse being disposed approximately in the direction of vibration of the member, a globule of mercury located in the chamber, and a pair of electrical contacts respectively located in the ends of the chamber for periodically engaging the mercury as it moves back and forth along the major axis of the chamber due to accelerations of the vibratory member.

8. The apparatus of claim 7 further including means connected to one oi the electrical contacts in the vibratory member for periodically energizing the electromagnet to accelerate the vibratory member.

9. An acceleration-responsive device comprising a globule of mercury having a volume which assumes spherical shape when unconfined, and a container located aeaemea around the globule and defining a chamber having a maximum cross-section which squashes the globule of mercury and limits the movement of the globule to movement along an axis of elongation of the chamber, the chamber having a greater volume than that of the globule of mercury so that the globule is located in the least confining portion of the chamber when at rest and moves into the more confining portions of the chamber only when the container is accelerated along the direction of said axis.

10. An electrical switch comprising a vibratory container defining a chamber having a cross-section of approximately elliptical shape in a plane extending along the direction of vibration of the container, with the major axis of the chamber being inclined with respect to the direction of vibration of the container, a globule of mercury located in the chamber so that the mercury is subjected to orbital movement around the periphery of the elliptical-shaped chamber, and contact means inside the chamber for providing an electrical circuit through the mercury when it is in a predetermined position in the chamber due to its orbital movement.

11. In a vibrating reed type relay having a vibratory member mounted on a resilient reed, and means for periodically accelerating the member along a predetermined direction, the improvement which comprises means in the vibratory member defining a chamber having a cross-section of approximately elliptical shape in a plane extending along the direction of vibration of the member, with the major axis of the chamber being inclined with respect to the direction of vibration of the member, a globule of mercury located in the chamber so that the mercury is subjected to orbital movement around the periphery of the elliptical-shaped chamber in synchronism with the vibrations of the member, and contact means inside the chamber for providing a short circuit through the mercury continually when the mercury is subjected to orbital movement around the periphery of the chamber.

12. A liquid switch which may be mounted in any position and is operated only by acceleration forces greater than the force of gravity, said switch comprising means defining an elongated hollowed chamber of substantially circular cross-section, a quantity of mercury in the chamher, the chamber having elongated end portions of diminishing cross-sectional diameter, electrodes positioned in the end portions of the chamber, the end of each of the respective electrodes terminating in the chamber within the respective end portions in a cross-sectional plane wherein the cross-sectional diameter is smaller than the minimum the cross-sectional diameter of the mercury will assume under the influence of the force of gravity, whereby acceleration forces greater than the force of gravity are required to force the mercury within the chamber into contact with one or the other of said electrodes.

13. A liquid switch which may be mounted in any position and is operated only by acceleration forces greater than the force of gravity, said switch comprising means defining an elongated hollow chamber of substantially circular cross-section, a quantity of mercury in the chamher, the chamber having elongated end portions of diminishing cross-sectional diameter, electrodes positioned in the end portions of the chamber, the electrodes terminating in the regions of the end portions of reduced crosssectional dimension into which the mercury will flow only under an accelerating force greater than the force of gravity.

References Cited in the file of this patent UNITED STATES PATENTS 292,193 Abdank-Abakanowicz Jan. 22, 1884 1,078,106 Miller Nov. 11, 1913 1,738,714 Keith Dec. 10, 1929 1,905,771 Walker Apr. 25, 1933 2,025,235 Gonsett Dec. 24, 1935 2,043,461 Phillips et al. June 9, 1936 2,259,953 Flanders et al Oct. 21, 1941 2,301,217 Lambert Nov. 10, 1942 2,634,377 Parker Apr. 7, 1953 FOREIGN PATENTS 269,346 Germany Mar. 18, 1913 

